A locomotive runs by picking up the electricity from the track through its wheels. The wheels transfer the electricity to the motor, which then turns the gears to drive the locomotive.

A locomotive with poor pickup on the wheels or a poor gear set up will give you lots of problems. As with most things, you get what you pay for . . .but this is one area you do not want to skimp on. A great operating locomotive is 90% of the way to having a fantastic model train layout.

When buying a locomotive these points are critical:

• The amount of metal wheels that pick up the electricity – the more the better, but definitely more than 1 set.
• A good gearing ratio and motor which requires the least amount of electricity to move the locomotive, with a slow but smooth start.
• Flywheels at one or both ends of the motor to ensure a smooth take off and smooth stop.
• The weight of the locomotive should be just right to maintain a good connection to the track at all times but not too heavy to make the locomotive sluggish. 
• The length of the locomotive – shorter diesel locomotives are less likely to derail on the curves than longer steam locomotives.

Most hobby shops will let you test the locomotive on their in-house test tracks before you buy.

Test the locomotive forwards and backwards; check for a nice smooth take off and a nice smooth stop when the power is ramped up or down.

I usually go into my local hobby shop after doing my research online, test the locomotive, and then purchase online.

That tip has saved me nearly 30% of the retail price in some cases.

Buy quality when you buy your locomotives; I guarantee the investment will be well worth it.

Related Articles:

1. How Model Train Locomotives Work
2. How to Shoot an Instructional Model Train Video; What You Need to Do to Make a Good Video
3. Model Railroad Electronics Provide Many Choices to Make Model Trains Perform Different Functions